linux-kernel - Re: [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more closely

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20101209225833.GA25750@srcf.ucam.org>
Date:	Thu, 9 Dec 2010 22:58:33 +0000
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	x86@...nel.org, linux-acpi@...r.kernel.org, lenb@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more
	closely

On Thu, Dec 09, 2010 at 02:53:35PM -0800, H. Peter Anvin wrote:
> On 12/09/2010 02:51 PM, Matthew Garrett wrote:
>> I'm afraid I don't understand your argument. The date cutoff would be on
>> the order of 2001 (anything after this will have been tested with XP).
>> The spec that defines this behaviour only came into existence in August
>> 2000, and any older hardware will be missing the flag that indicates
>> that this feature is supported. It doesn't seem realistic to believe
>> that there's any real body of hardware that sets the flag but otherwise
>> has a broken implementation.
>>
>
> 2001 is probably a good date, then.
>
> It's pretty safe you'll see the bit being set on systems which are older  
> than that, even if it was not defined at the time it was created -- just  
> being garbage.  That's par for the course in BIOS land.

There's a revision field in the FADT. They'd need to simultaneously 
provide an incorrect revision *and* by pure luck set the 10th bit of a 
32-bit register. Is it possible? Yes. Is it likely? No, and I don't see 
a benefit in adding extra code to force hardware into a less-tested 
configuration.

-- 
Matthew Garrett | mjg59@...f.ucam.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/